Help! could anyone do me a favor

[admin]

Hi, I
got a problem and seeking for help, could anyone do me a favor.

 

The
power supply of network data centre is supplied by a UPS. The UPS’s output
connects to 2 nos. of 800A MCCB individually. And the circuits are protected by:

( Form 
 >>   to )

 

A)    800A MCCB  >> 
100A MCCB  >>  100A AI switch  >> 
( circuit 1 & 2 )

 

1)     63A Type C MCB  >> 
63A AI switch  >>  32A RCBO 
>>  Power socket  

2)     63A Type B MCB  >> 
Floor box (40A RCCB + Power socket)

 

B)     800A MCCB  >> 
100A MCCB  >>  100A AI switch  >> 
63A Type B MCB  >>  Floor box (40A RCCB + Power socket)

 

The case is that, a fault occurred at data server that
supply by the power socket of circuit A(1). The 32A RCBO was
tripped. When I tried to reset the RCBO, it tripped again immediately. At the
mean time, an unpredictable scenario was happened. Some RCCB (around 6 nos.) at circuit A(2) and circuit B were tripped at
the same time immediately. That caused around 7 nos. of servers were downed. Could
anyone do me a favor to give a hint? Thanks you so much.

[Marcolao]

marcolao said:

Hi, I

got a problem and seeking for help, could anyone do me a favor.

 

The

power supply of network data centre is supplied by a UPS. The UPS’s output

connects to 2 nos. of 800A MCCB individually. And the circuits are protected by:

( Form 

 >>   to )

 

A)    800A MCCB  >> 

100A MCCB  >>  100A AI switch  >> 

( circuit 1 & 2 )

 

1)     63A Type C MCB  >> 

63A AI switch  >>  32A RCBO 

>>  Power socket  

2)     63A Type B MCB  >> 

Floor box (40A RCCB + Power socket)

 

B)     800A MCCB  >> 

100A MCCB  >>  100A AI switch  >> 

63A Type B MCB  >>  Floor box (40A RCCB + Power socket)

 

The case is that, a fault occurred at data server that

supply by the power socket of circuit A(1). The 32A RCBO was

tripped. When I tried to reset the RCBO, it tripped again immediately. At the

mean time, an unpredictable scenario was happened. Some RCCB (around 6 nos.) at circuit A(2) and circuit B were tripped at

the same time immediately. That caused around 7 nos. of servers were downed. Could

anyone do me a favor to give a hint? Thanks you so much.

---

No MCCB or MCB was tripped, only the the RCCBs were
affected. That caused around 7 nos. of servers downed. Finally, a fault
equipment at circuit A(1) had been isolated, and all circuits had been reset.
My question is that ;

1) Why the other RCCBs at the final circuit of the
separated circuits were tripped during I reset aforesaid  RCBO?

2) How the fault affect separated circuits?

[Spir Georges GHALI]

Dear ;

 

Even the schematic diagram is not too clear, but i will try to explain what could be happen.

 

As the RCBO tripped, and we know that all RCBO have ” Thermal & Magnetic protections + Earth Leakage protection ” there's 2 possibilities :

     1 – The tripping order was from ” Thermal or Magnetic protection ” and in this case we had either an over-load or short circuit, where we can know which of them as follow : if you tried to close it without success for a few minutes in this case the tripping's order was from Thermal protection, or it closed but immediately re-tripped in this case the tripping's order was from Magnetic protection.

     2 – The tripping order was from Earth Leakage protection, and in this case we have 3 possibilities :

          A – There's a leakage current, either permanent or transient, more than ” IΔn “, if permanent you can't re-close the RCBO, but if transient you can re-close it again.

          B – We know all the all kind of PC have a transiant leakage current and a big value of Crest factor that cause some distortion of the current, for these reasons we use for this kind of application a special RCBO or RCCB that have ” High Immunity “.

          C – At the moment of supplying a PC the inrush current is, in some case, bigger than the Magnetic protection, so, the RCBO will re-trip immediately. for this reason it will be better to use ” C curve ” or in some case ” D curve “.

 

To be able to clarify more, it will be better to have the Single Line Diagram, because as you mentioned that there's 800A MCCB, then 100A MCCB and 100A I Switch, then 63A MCB and 63A Switch, then the RCBO or RCCB.

[Author]

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